Changeset: 3fd82fe82475 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/3fd82fe82475
Modified Files:
monetdb5/optimizer/opt_mitosis.c
monetdb5/optimizer/opt_mitosis.h
Branch: Dec2025
Log Message:
Decrease maximum number of slices into which a table is partitioned.
diffs (68 lines):
diff --git a/monetdb5/optimizer/opt_mitosis.c b/monetdb5/optimizer/opt_mitosis.c
--- a/monetdb5/optimizer/opt_mitosis.c
+++ b/monetdb5/optimizer/opt_mitosis.c
@@ -13,6 +13,7 @@
#include "mal_interpreter.h"
#include "gdk_utils.h"
+#define MAXSLICES 128 /* to be refined */
#define MIN_PART_SIZE 100000 /* minimal record count per partition */
#define MAX_PARTS2THREADS_RATIO 4 /* There should be at most this
multiple more of partitions than threads */
@@ -21,15 +22,19 @@ str
OPTmitosisImplementation(Client cntxt, MalBlkPtr mb, MalStkPtr stk,
InstrPtr pci)
{
- int i, j, limit, slimit, pieces = 1, mito_parts = 0,
- mito_size = 0, row_size = 0, mt = -1, nr_cols = 0, nr_aggrs = 0,
- nr_maps = 0;
- str schema = 0, table = 0;
- BUN r = 0, rowcnt = 0; /* table should be sizeable to consider
parallel execution */
+ int i, j, limit, slimit, pieces = 1, mito_parts = 0;
+ int mito_size = 0, row_size = 0, mt = -1, nr_cols = 0, nr_aggrs = 0;
+ int nr_maps = 0;
+ const char *schema = NULL;
+ const char *table = NULL;
+ BUN r = 0;
+ BUN rowcnt = 0; /* table should be sizeable to consider
parallel execution */
InstrPtr p, q, *old, target = 0;
- size_t argsize = 6 * sizeof(lng), m = 0;
+ size_t argsize = 6 * sizeof(lng);
+ size_t m = 0;
/* estimate size per operator estimate: 4 args + 2 res */
- int threads = GDKnr_threads ? GDKnr_threads : 1, maxparts = MAXSLICES;
+ int threads = GDKnr_threads ? GDKnr_threads : 1;
+ int maxparts = MAXSLICES;
str msg = MAL_SUCCEED;
/* if the user has associated limitation on the number of threads,
respect it in the
@@ -58,7 +63,7 @@ OPTmitosisImplementation(Client cntxt, M
/* mitosis/mergetable bailout conditions */
/* Crude protection against self join explosion */
- if (p->retc == 2 && isMatJoinOp(p))
+ if (p->retc == 2 && isMatJoinOp(p) && threads < maxparts)
maxparts = threads;
nr_aggrs += (p->argc > 2 && getModuleId(p) == aggrRef);
@@ -186,7 +191,7 @@ OPTmitosisImplementation(Client cntxt, M
* |threads| partitions at a time fit in memory,
* i.e., (threads*(rowcnt/pieces) <= m),
* i.e., (rowcnt/pieces <= m/threads),
- * i.e., (pieces => rowcnt/(m/threads))
+ * i.e., (pieces >= rowcnt/(m/threads))
* (assuming that (m > threads*MIN_PART_SIZE)) */
/* the number of pieces affects SF-100, going beyond 8x
increases
* the optimizer costs beyond the execution time
diff --git a/monetdb5/optimizer/opt_mitosis.h b/monetdb5/optimizer/opt_mitosis.h
--- a/monetdb5/optimizer/opt_mitosis.h
+++ b/monetdb5/optimizer/opt_mitosis.h
@@ -12,8 +12,6 @@
#define _OPT_MITOSIS_
#include "opt_support.h"
-#define MAXSLICES 1024 /* to be refined */
-
extern str OPTmitosisImplementation(Client cntxt, MalBlkPtr mb, MalStkPtr stk,
InstrPtr p);
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